每消耗1mol原子氧時所消耗的用於ADP磷酸化的無機磷酸中的磷原子摩爾數，即每消耗1mol原子氧時生成的ATP的摩爾數。
指物質氧化時，每消耗1mol
氧原子所消耗
無機磷的摩爾數(或ADP摩爾數)，即生成ATP的摩爾數。
The P/O ratio is the number of molecules of ATP formed in oxidative phosphorylation per two electrons flowing through a defined segment of the electron transport chain.